Ceiling mounted fans are often used for circulating air within large buildings such as warehouses, factories, gymnasiums, churches, auditoriums, convention centers, theaters, and other buildings with large open areas. For fire safety, sprinkler heads are usually installed near the ceiling and are used for spraying water or other fire-suppressing media on any fires that might occur within the building. In the event of a fire, the fans can be turned off to avoid fanning the fire while the sprinklers are activated to quench the fire.
In some cases, a sprinkler head might be installed directly above the fan blades. In such situations, the fan blades might obstruct or interfere with the water spraying from the sprinkler head, regardless of whether the fan blades are rotating or stationary. Although it might be possible to relocate the fan or sprinkler so that they are farther apart, large diameter fans can be particularly difficult to fit among a relatively dense matrix of sprinkler heads.
A similar interference problem might occur between a ceiling fan and a nearby overhead light fixture. Fan blades rotating underneath a light fixture might not be much of a problem; however, if one of the fan blades stops directly underneath the light when the fan turns off, that single stationary fan blade might block a noticeable amount of light.